The subject matter herein generally relates to chemical detection systems and, more particularly, to chemical detection systems that include one or more ion mobility spectrometers and mass spectrometers.
Chemical detection systems are used to detect particular threats. These threats include explosives, illicit drugs, chemical warfare agents, pollutants, and toxins, for example. Many of these detection systems include ion mobility spectrometers. The ion mobility spectrometers measure the presence of ions obtained from analytes in a sample. The ions are created by ionizing vapor molecules from the sample. The sample is obtained in the form of vapors from ambient air or in the form of particulate matter from ambient air, a package, luggage or person that is being examined for explosives, drugs or other chemical agents.
The ions that are obtained from the analytes in the sample are represented as peaks on an ion mobility spectrum. The peaks in the spectrum are used to determine whether a particular ion of interest is present in the sample. An ion of interest is an ion that is associated with a particular analyte of interest. An analyte of interest is a chemical species that commonly is found with the explosives, drugs, chemical warfare agents, and other chemicals that are sought to be detected.
One problem associated with ion mobility spectrometers is the resolution of the spectrometers. In some cases, known spectrometers may have difficulty in distinguishing between chemicals present in the background of the sample and the analytes of interest. These devices can produce false positive and false negative alarms. A false positive alarm occurs when the spectrometer misinterprets a peak in a spectrum as representing a threat. A false negative alarm occurs when the spectrometer misinterprets a peak in a spectrum that corresponds to an analyte of interest as corresponding to an analyte that is not of interest. A false negative alarm also may occur when a peak of interest is suppressed or obscured by other peaks. These other peaks may be associated with other analytes in the sample that are not analytes of interest.
Thus, a need exists for an improved chemical detection system that more accurately detects the presence of one or more analytes of interest in a sample. Such a system can improve existing procedures for detecting explosives, illicit drugs, chemical warfare agents, toxins or pollutants.